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Old 9th September 2012, 01:39 PM   #291
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Quote:
Originally Posted by JLH View Post
If you are shooting for 40 degrees vertical then the paraline will need to be tall and skinny looking.
It is. 10" tall x 4" wide. Maybe not enough?
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Old 9th September 2012, 09:11 PM   #292
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Originally Posted by jwmbro View Post
... The general consensus in this thread seems to be that the paraline is a (quasi-)conical horn. I disagree. In my opinion it must be a parabolic horn, as the cross sectional area expands linearly with path length (A = 2*pi*r*h, h=const) whereas for a conical expansion rate, the area would need to expand quadratically with the path length (A = pi*r^2) .
Shhh... you'll be branded a heretic like I was.
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Old 9th September 2012, 09:21 PM   #293
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Originally Posted by natehansen66 View Post
It is. 10" tall x 4" wide. Maybe not enough?
You'll need to do some trigonometry.
This post shows how it looks for a "standard" Paraline:

Square Pegs

You'll need to move the focus closer to the vertex (same as making the curve shallower) to get your desired vertical dispersion.
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Old 9th September 2012, 09:27 PM   #294
JLH is offline JLH  United States
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Quote:
Originally Posted by natehansen66 View Post
It is. 10" tall x 4" wide. Maybe not enough?
That sounds about right.
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Old 9th September 2012, 11:06 PM   #295
JLH is offline JLH  United States
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Out of my own curiosity I decided to compare the parabolic, exponential, and conical profiles. I started with the same throat areas and ended with approximately the same mouth areas along the same distances. I overlaid the three to see how close they were to each other. The parabolic and conical practically lay on top of each other. The exponential deviates from the other two by quite a bit. This is what I meant when I said the paraline approximates the conical profile. Go ahead and try this yourself. I was actually surprised how close the parabolic and conical are. I double and triple checked my calculations to be sure before I posted this. Nothing like looking like a fool in front of the whole internet. I think we are dealing with a situation where these line up closely due to the areas and distances we are working with. If you extend these out to a more extreme example, I think you would start to see them separate. This is very much like how the tractrix and exponential are impossible to distinguish from one another near the throat of the horn.
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File Type: png Paraline_flare_compare.png (134.3 KB, 412 views)
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Old 9th September 2012, 11:33 PM   #296
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Originally Posted by JLH View Post
... Nothing like looking like a fool in front of the whole internet. ...
Your apology is accepted.

.. but seriously, I see your point. "Approximately conic" is close enough.

Last edited by Don Hills; 9th September 2012 at 11:38 PM.
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Old 10th September 2012, 12:56 AM   #297
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Have I missed the Idiots Guide to Paralines?

I have some 3" Fullrangers and some tiny itty bitty Apex Jr Tweeters. Any chance they will work in a rough experiment?

From what I understand we are working at quarter wavelengths like other horns and thus 100Hz is a 85cm or 33.5" slot on the front? The idea of a "small/compact" synergy/unity horn that reaches 100-90Hz is something I would really like.

I might have missed it in the discussion but would building a "normal" synergy horn with the mids mounted on the sides of the horn, but using paralines to help load the mids into the horn be helpful in pushing the low end response of diy synergy down, while also trying to minimise size?

Sorry for all the possibly repetitive/dumb questions, I kind of got lost when we started arguing about what type of horn it is. My horn theory is a tad rusty (*cough* non-existant *cough*). But I am very interested in these paralines as the one thing limiting me from horns is space.
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Old 10th September 2012, 01:16 AM   #298
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Mitch311,
It really doesn't matter what size devices that you start with. Think about the fact that you still have to expand the flare at a reasonable rate and you can start to see that the smaller the given driver the longer a horn gets to reach the same mouth size. A 90 to 100hz mouth is not small, that is large no matter if it is conic or exponential in configuration. I wouldn't count on making any real output with a 3" device at 100hz, the excursion is just so small. Take the speed of sound in inches or meters per second, divide by the frequency and divide that by 4 and you have your wavelength. That would be the diameter of a circle at cutoff. Approximately 13,548/100/4 = 33.87 inches in diameter. Simple math unless I am brain dead today. Same for the length of a normal horn but perhaps with the paraline it can be shorter. I will let the paraline guys answer that one.
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Old 10th September 2012, 01:42 AM   #299
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Hi Kindhornman,

Your name is appropriate . I don't expect to reach 100Hz with a 3" driver. I'd just like to fiddle with some new speakers and actually get to listen to some horns/synergy-style-horns in real life, even if limited to 300Hz or so extension, as everyone I have seen write about them has been thoroughly impressed.

I understand the horn mouths are going to be large for a 100Hz or lower horn. That is not so much the limitation as depth is. I can't have the horn mouth sitting a meter out into my lounge room from the wall.

My assumption from reading this discussion has been that the paraline helps load the driver in effect providing more horn length with little actual physical depth. It also helps shape the output, which when/if combined with a "traditional" horn provides more frequency extension and directional control ( depending on shape/size of the paraline) than one would predict from a "traditional" horn of a given size/depth.

I don't know if I am going in the right direction here, but my hope is to build horn loaded tops (preferably in a point source imitating style aka synergy) that are no more than say 30-40cm deep, but of essentially any other given size, that I could cross at 100-90Hz to subwoofers. This might be a TOTALLY unrealistic goal, I am here to learn, and was drawn to this paraline innovation by Patrick Bateman saying they only take a few hrs to experiment with.
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Old 10th September 2012, 01:54 AM   #300
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Mitch,
I only know so much about these paralines from reading and interacting on this thread. Yes the initial length of horn very short during the initial expansion. But beyond the initial flat section you sill are attaching a conic horn section to produce the low frequency extension. So if we think that the first section is 1/4 of the overall length you will still have roughly another 25 inches of length. So you would still have a substantial length of flare. I will wait for someone like Patrick to answer this question with more authority.

Steven
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